Process for utilizing light metal scrap



Patented Aug. 27, 1929.

UNITED STATES HENRY CHAMBERLAIN, OF LOS ANGELES, CALIFORNIA.

PROCESS FOR UTILIZING LIGHT METAL SCRAP.

No Drawing.

This invention has to do with a process for making light metal scraps into metal useful in the manufacture of various prod nets.

There are quantities of light metal scraps, or light weight waste metal parts, that are ordinarily thrown away. As an example, I will refer to tin cans, and the like. Various processes have from time to time been proposed and used for handling such scraps to recover the metals so that they can be used for otherpurposes. These processes, while in commercial use, have not been entirely satisfactory.

It is a primary object of my present invention to provide an inexpensive and efficient process of handling metal scrap to produce useful metal.

It is another object of this invention to provide an improved process of handling metal scrap whereby carbon, or the like, can

. be introduced in a manner to be combined in the resultant metal. 7

Another object ofthe invention is to provide a process whereby carbon, or the like, is effectively and uniformly introduced into the metal without agitation or puddling.

It is another object of this invention to provide a process of the character mentioned which can be carried out successfuly with comparatively little handling of the materials and at comparatively low temperatures.

A further object of the invention is to provide a process whereby carbon, or the like,

is introduced directly into the metal scrap, thus eliminating the use of carbonized iron, or the like.

My present invention is applicable to metal scraps of various kinds. I have, however, found it commercially valuable in handling tinned scraps, for example, tin cans. I will, for purpose of example, set forth a typical detailed application of the invention as appied to tin cans, or the like, it being understood that suitable variations may be made in applying the invention to material of varying character.

The scraps to be handled or worked are first treated to clean them of tin or galvanizing. There are several known methods of de-tinning or de-galvanizing metal and, as far as my present invention is concerned, any suitable method may be employed in preparing the metal for treatment by my process.

The metal, when made ready for my proc- Application filed April 4,

1927. Serial No. 181,006.

ess and while in a loose state, has added to r it, or mixed with it, the element or material desired to be combined in the finished product. For example, if it is desired that the finished product have a high carbon content, carbon is mixed with the loose metal scrap. In practice, any suitable commercial form of carbon, such as ground charcoal, may be used, it being preferred that the carbon be in a finely divided state so that it may be well distributed throughout the bulk of metal. The amount of carbon used may vary considerably, depending upon circumstances or the desired analysis of the finished product. In practice, I have found it advantageous to use about five pounds of charcoal to one hundred and fifty pounds of metal.

The mixture of metal scrap and carbon is compressed while cold to reduce its bulk and facilitate handling. In practice, I have found it economical to compress the cold mixture until it is about twenty-five to fiftyper. cent of the weight of cast iron. It is obvious, of course, that the amount of pressure required to bring the mixture to thisstate will vary, depending upon the character of the scrap, the amount compressed in a single body, etc. In practice, this cold compression of the mixture of scrap and carbon may be carried out in any suitable pressing or baling apparatus. It is convenient, in practice, to compress the mixture of carbon and metal scrap into bales weighing from one hundred to two hundred pounds, as bales of this size can be conveniently handled through the subsequent steps of the process.

The bodies of mixed metal scrap and carbon are then heated slowly until the entire mass is brought to a welding heat which, in practice, is about 2200 degrees Fahrenheit. 5 Any small amounts of tin, or other like impurities are volatilized and expelled, leaving the mixture which reaches the welding temperature a substantially pure mixture of iron and carbon. When I use the term iron I 100 mean to include not only iron but also steel. During the heating of the mixture and after the mixture is at the welding temperature, a large percentage of carbon is taken up or combined with the metal. I have found that 105 this uniting of the carbon and metal is very complete and effective as the metal scrap is usually comparatively light or thin and thus allows the carbon to penetrate to all parts. When I use the term slowly in 110 referring to the process of bringing the mixture of scrap and carbon to the welding temperature, I mean to use the term gener ally and I refer to a rate which allows sufficient time for the proper combining of the metal and carbon and for the bringing of the mass to the desired temperature more or less uniformly with a minimum of burning or oxidation. In practice, bodies or bales of mixed metal scrap and carbon are ordinarily subjected to the desired heat treatment and brought to the Welding temperature in aboutthirty I'ninutes.

The mass of scrap metal with the carbon is taken'at the Welding temperature and is pressed, bringing the metal parts together so that they Weld or unite into a solid body of metal. As the metal is pressed, any slag or impurities, such as glass, crockery, etc, are squeezed out of the mass. This last pressing operation may be carried out in presses designed for the purpose, it being preferred to use pre-heated dies so that the mass is maintained as nearly as possible at the Welding temperature during the pressing operation. In practice, I have found that satisfactory results are obtained upon pressingthe mass under about eight thousand pounds pressure per square inch.

The metal obtained as a result of the pressing operation just described may be taken from the'hot press and While still at a forging heat may be cut, rolled, drop forged, or 1 otherwise formed into' suitable commercial products.

I have found that by carrying out my process as above described, I obtain a metal having a high carbon content which is, of course, very desirable for many purposes. In actual operation, I have successfully treated a mixture of one hundred and fifty pounds metal scrap and five pounds carbon and obtained a resulting metal showing by analysis .75 combined carbon.

I Wish to call particular attention to the fact that the mixture of carbon and iron is heated quickly or Without agitation and that no elements are added during heating.

Having described only a typical preferred form of my invention, I do not Wish to limit myself to the specific details set forth, but Wish to reserve to myself any changes or variations that ma appear to those skilled in the art or fall Wltllll] the scope of the following claim.

-Having described my invention, I claim.

'The herein described process of forming a body of metal including intimately mixing scrap sheet metal and finely divided carbon, pressing the metal and carbon cold to form bales, heating the bales to about 2200 degress Fahrenheit, and then subjecting the heated bales to' a high pressure to form solid bodies of metal.

In Witness that I claim. the foregoing I have hereunto subscribed my name this 30th day of March, l927.

, HENRY CHAMBERLAIN. 

